// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2019, Linaro Limited, All rights reserved.
 * Author: Mike Leach <mike.leach@linaro.org>
 */

#include <linux/device.h>
#include <linux/kernel.h>

#include "coresight-priv.h"

/*
 * Connections group - links attribute.
 * Count of created links between coresight components in the group.
 */
static ssize_t nr_links_show(struct device *dev,
                             struct device_attribute *attr,
                             char *buf)
{
        struct coresight_device *csdev = to_coresight_device(dev);

        return sprintf(buf, "%d\n", csdev->nr_links);
}
static DEVICE_ATTR_RO(nr_links);

static struct attribute *coresight_conns_attrs[] = {
        &dev_attr_nr_links.attr,
        NULL,
};

static struct attribute_group coresight_conns_group = {
        .attrs = coresight_conns_attrs,
        .name = "connections",
};

/*
 * Create connections group for CoreSight devices.
 * This group will then be used to collate the sysfs links between
 * devices.
 */
int coresight_create_conns_sysfs_group(struct coresight_device *csdev)
{
        int ret = 0;

        if (!csdev)
                return -EINVAL;

        ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
        if (ret)
                return ret;

        csdev->has_conns_grp = true;
        return ret;
}

void coresight_remove_conns_sysfs_group(struct coresight_device *csdev)
{
        if (!csdev)
                return;

        if (csdev->has_conns_grp) {
                sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
                csdev->has_conns_grp = false;
        }
}

int coresight_add_sysfs_link(struct coresight_sysfs_link *info)
{
        int ret = 0;

        if (!info)
                return -EINVAL;
        if (!info->orig || !info->target ||
            !info->orig_name || !info->target_name)
                return -EINVAL;
        if (!info->orig->has_conns_grp || !info->target->has_conns_grp)
                return -EINVAL;

        /* first link orig->target */
        ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
                                      coresight_conns_group.name,
                                      &info->target->dev.kobj,
                                      info->orig_name);
        if (ret)
                return ret;

        /* second link target->orig */
        ret = sysfs_add_link_to_group(&info->target->dev.kobj,
                                      coresight_conns_group.name,
                                      &info->orig->dev.kobj,
                                      info->target_name);

        /* error in second link - remove first - otherwise inc counts */
        if (ret) {
                sysfs_remove_link_from_group(&info->orig->dev.kobj,
                                             coresight_conns_group.name,
                                             info->orig_name);
        } else {
                info->orig->nr_links++;
                info->target->nr_links++;
        }

        return ret;
}

void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
{
        if (!info)
                return;
        if (!info->orig || !info->target ||
            !info->orig_name || !info->target_name)
                return;

        sysfs_remove_link_from_group(&info->orig->dev.kobj,
                                     coresight_conns_group.name,
                                     info->orig_name);

        sysfs_remove_link_from_group(&info->target->dev.kobj,
                                     coresight_conns_group.name,
                                     info->target_name);

        info->orig->nr_links--;
        info->target->nr_links--;
}

/*
 * coresight_make_links: Make a link for a connection from a @orig
 * device to @target, represented by @conn.
 *
 *   e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
 *   as two symbolic links :
 *
 *      /sys/.../devOrig/out:X  -> /sys/.../devTarget/
 *      /sys/.../devTarget/in:Y -> /sys/.../devOrig/
 *
 * The link names are allocated for a device where it appears. i.e, the
 * "out" link on the master and "in" link on the slave device.
 * The link info is stored in the connection record for avoiding
 * the reconstruction of names for removal.
 */
int coresight_make_links(struct coresight_device *orig,
                         struct coresight_connection *conn,
                         struct coresight_device *target)
{
        int ret = -ENOMEM;
        char *outs = NULL, *ins = NULL;
        struct coresight_sysfs_link *link = NULL;

        do {
                outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
                                      "out:%d", conn->outport);
                if (!outs)
                        break;
                ins = devm_kasprintf(&target->dev, GFP_KERNEL,
                                     "in:%d", conn->child_port);
                if (!ins)
                        break;
                link = devm_kzalloc(&orig->dev,
                                    sizeof(struct coresight_sysfs_link),
                                    GFP_KERNEL);
                if (!link)
                        break;

                link->orig = orig;
                link->target = target;
                link->orig_name = outs;
                link->target_name = ins;

                ret = coresight_add_sysfs_link(link);
                if (ret)
                        break;

                conn->link = link;

                /*
                 * Install the device connection. This also indicates that
                 * the links are operational on both ends.
                 */
                conn->child_dev = target;
                return 0;
        } while (0);

        return ret;
}

/*
 * coresight_remove_links: Remove the sysfs links for a given connection @conn,
 * from @orig device to @target device. See coresight_make_links() for more
 * details.
 */
void coresight_remove_links(struct coresight_device *orig,
                            struct coresight_connection *conn)
{
        if (!orig || !conn->link)
                return;

        coresight_remove_sysfs_link(conn->link);

        devm_kfree(&conn->child_dev->dev, conn->link->target_name);
        devm_kfree(&orig->dev, conn->link->orig_name);
        devm_kfree(&orig->dev, conn->link);
        conn->link = NULL;
        conn->child_dev = NULL;
}